We use two steps: 1. Insert a medical-grade endoscope through the spark plug hole to visually inspect cylinder wall scratches and carbon buildup on the piston top; 2. Extract an engine oil sample to check for large metal debris or emulsification (caused by coolant leakage).

Air suspension is very delicate. If, after the vehicle has been stationary for about 12 hours, the height on one side of the vehicle drops more than 1.5 cm when measured from the wheel arch to the tire, we will determine that there is a slight air leak in the air spring or distribution valve on that side and warn you of the high subsequent repair costs.

If the car has been maintained at an authorized dealer, we can extract the desensitized official maintenance history (including entry time, mileage, and maintenance items) through a paid third-party data provider and provide it to you. If some year records are missing, we will honestly inform you that the "records are incomplete."